Aerosol-generating system with adjustable pump flow rate

ABSTRACT

A method of generating an aerosol in an aerosol-generating system includes storing liquid aerosol-forming substrate in a liquid storage portion and delivering via a pump a liquid aerosol-forming substrate from the liquid storage portion to an atomizer. The method also includes sensing a puff via a a puff sensor in an airflow path of the aerosol-generating system and determining a puff intensity during the puff via a controller. The delivery flow rate of the liquid aerosol-forming substrate to the atomizer is adjusted in response to the determined puff intensity.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/889,043, filed Jun. 1, 2020, which is a continuation of U.S.application Ser. No. 15/825,548, filed Nov. 29, 2017, which is acontinuation of, and claims priority to, international application no.PCT/EP2017/077666, filed on Oct. 27, 2017, and further claims priorityunder 35 U.S.C. § 119 to European Patent Application No. 16201194.4,filed Nov. 29, 2016, the entire contents of each of which areincorporated herein by reference.

BACKGROUND Field

Example embodiments relate to an aerosol-generating system (which mayalso be referred to as electronic vaping systems) comprising a pump, anatomizer and a puff sensor. The delivery flow rate of the pump isadjusted in response to a desired (or, alternatively predetermined) puffintensity. Example embodiments also relate to a corresponding method forgenerating an aerosol.

Description of Related Art

Aerosol-generating systems available may comprise a vaporizer employinga wick-and-coil arrangement. A part of a capillary wick may extend intoa liquid storage portion containing e-liquid to be volatilized. Anotherpart of the wick may be at least partially surrounded by a coil ofheating wire. Upon application of an electric current, the heating wireevaporates the e-liquid contained in the wick. Dose delivery may bedifficult to control as it may depend on the puff frequency of the vaperand on the capillary properties of the wick.

In another type of aerosol-generating systems a reservoir, a micropumpand a vaporizer may be included. During a puff, a constant stream ofe-liquid is actively pumped from the liquid storage portion to thevaporizer. The flow rate of the micropump is kept constant such that anactive control of the delivered dose is achieved. In this way ahomogenous delivery of nicotine during an inhaling experience isprovided.

It has been noted that a vaper's preference may vary, as some vapersprefer a more intensive puffing regime than others.

SUMMARY

At least one example embodiment relates to an aerosol-generating system.

In at least one example embodiment, an aerosol-generating systemcomprises a housing including an air inlet and an air outlet, an airflowpath defined between the air inlet and the air outlet; vaporizerconfigured to vaporize an aerosol-forming substrate, the vaporizerincluding, a heating element; a liquid storage portion configured tocontain the aerosol-forming substrate; a pump configured to deliver theaerosol-forming substrate from the liquid storage portion to thevaporizer; a puff sensor in the airflow path, the puff sensor configuredto sense a puff, and a controller connected to the puff sensor and tothe heating element, the controller configured to determine a puffintensity based on an output from the puff sensor and adjust a deliveryflow rate of the pump and the electrical power supplied to the heatingelement in response to the determined puff intensity.

In at least one example embodiment, the puff sensor is one of a pressuresensor or an airflow sensor.

At least one example embodiment relates to a method of generating anaerosol.

In at least one example embodiment, a method of generating an aerosolcomprises pumping a liquid aerosol-forming substrate from a liquidstorage portion to a vaporizer using a pump, the vaporizer including, aheating element configured to vaporize the liquid aerosol-formingsubstrate; sensing a puff using a puff sensor, the puff sensor in anairflow path of the aerosol-generating system, the puff sensorconfigured to sense a puff; and determining, using a controller, a puffintensity by comparing an output from the puff sensor with values storedin a look-up table, the controller configured to adjust a delivery flowrate of the pump and electrical power supplied to the heating element inresponse to the determined puff intensity.

In at least one example embodiment, the puff intensity is based on apuff sensor reading obtained after about 0.1 seconds to about 0.9seconds after initiation of the puff.

In at least one example embodiment, the sensing includes at least one ofdetecting the initiation of the puff by the puff sensor, or detectingthe initiation of the puff by an activating a button.

In at least one example embodiment, the method may further includeadjusting the electrical power supplied to the heating element inresponse to the delivery flow rate of the liquid aerosol-formingsubstrate.

In at least one example embodiment, the method may include activatingthe pump until an end of the puff is detected.

In at least one example embodiment, the method may include pre-heatingthe heating element upon initiation of a puff.

In at least one example embodiment, the method may include activatingthe heating element for the duration of the puff.

In at least one example embodiment, the method may include activatingthe heating element for an additional predefined period of time about0.5 seconds after the pump has been deactivated.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will not be described, by way of example only.

FIG. 1 is illustration of an aerosol-generating system in accordancewith at least one example embodiment.

FIG. 2 is a graph showing experimental measurements of the relativepressure within an aerosol-generating system during a puff according toat least one example embodiment.

DETAILED DESCRIPTION

Example embodiments will become more readily understood by reference tothe following detailed description of the accompanying drawings. Exampleembodiments may, however, be embodied in many different forms and shouldnot be construed as being limited to the example embodiments set forthherein. Rather, these example embodiments are provided so that thisdisclosure will be thorough and complete. Like reference numerals referto like elements throughout the specification.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a”, “an” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. It willbe further understood that the terms “comprises,” “comprising,”“includes,” and/or “including,” when used in this specification, specifythe presence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

It will be understood that when an element or layer is referred to asbeing “on”, “connected to” or “coupled to” another element or layer, itcan be directly on, connected or coupled to the other element or layeror intervening elements or layers may be present. In contrast, when anelement is referred to as being “directly on”, “directly connected to”or “directly coupled to” another element or layer, there are nointervening elements or layers present. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, components, regions, layersand/or sections, these elements, components, regions, layers and/orsections should not be limited by these terms. These terms are only usedto distinguish one element, component, region, layer or section fromanother region, layer or section. Thus, a first element, component,region, layer or section discussed below could be termed a secondelement, component, region, layer or section without departing from theteachings set forth herein.

Spatially relative terms, such as “beneath”, “below”, “lower”, “above”,“upper”, and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the example term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

Example embodiments are described herein with reference to cross-sectionillustrations that are schematic illustrations of idealized embodiments(and intermediate structures). As such, variations from the shapes ofthe illustrations as a result, for example, of manufacturing techniquesand/or tolerances, are to be expected. Thus, these example embodimentsshould not be construed as limited to the particular shapes of regionsillustrated herein, but are to include deviations in shapes that result,for example, from manufacturing. For example, an implanted regionillustrated as a rectangle will, typically, have rounded or curvedfeatures and/or a gradient of implant concentration at its edges ratherthan a binary change from implanted to non-implanted region. Likewise, aburied region formed by implantation may result in some implantation inthe region between the buried region and the surface through which theimplantation takes place. Thus, the regions illustrated in the figuresare schematic in nature and their shapes are not intended to illustratethe actual shape of a region of a device and are not intended to limitthe scope of this disclosure.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art. It will be further understood that terms,such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and this specification and will not beinterpreted in an idealized or overly formal sense unless expressly sodefined herein.

Unless specifically stated otherwise, or as is apparent from thediscussion, terms such as “processing” or “computing” or “calculating”or “determining” or “displaying” or the like, refer to the action andprocesses of a computer system, or similar electronic computing device,that manipulates and transforms data represented as physical, electronicquantities within the computer system's registers and memories intoother data similarly represented as physical quantities within thecomputer system memories or registers or other such information storage,transmission or display devices.

In the following description, illustrative embodiments may be describedwith reference to acts and symbolic representations of operations (e.g.,in the form of flow charts, flow diagrams, data flow diagrams, structurediagrams, block diagrams, etc.) that may be implemented as programmodules or functional processes including routines, programs, objects,components, data structures, etc., that perform particular tasks orimplement particular abstract data types. The operations be implementedusing existing hardware in existing electronic systems, such as one ormore microprocessors, Central Processing Units (CPUs), digital signalprocessors (DSPs), application-specific-integrated-circuits (ASICs),SoCs, field programmable gate arrays (FPGAs), computers, or the like.

One or more example embodiments may be (or include) hardware, firmware,hardware executing software, or any combination thereof. Such hardwaremay include one or more microprocessors, CPUs, SoCs, DSPs, ASICs, FPGAs,computers, or the like, configured as special purpose machines toperform the functions described herein as well as any other well-knownfunctions of these elements. In at least some cases, CPUs, SoCs, DSPs,ASICs and FPGAs may generally be referred to as processing circuits,processors and/or microprocessors.

Although processes may be described with regard to sequentialoperations, many of the operations may be performed in parallel,concurrently or simultaneously. In addition, the order of the operationsmay be re-arranged. A process may be terminated when its operations arecompleted, but may also have additional steps not included in thefigure. A process may correspond to a method, function, procedure,subroutine, subprogram, etc. When a process corresponds to a function,its termination may correspond to a return of the function to thecalling function or the main function.

As disclosed herein, the term “storage medium”, “computer readablestorage medium” or “non-transitory computer readable storage medium,”may represent one or more devices for storing data, including read onlymemory (ROM), random access memory (RAM), magnetic RAM, core memory,magnetic disk storage mediums, optical storage mediums, flash memorydevices and/or other tangible machine readable mediums for storinginformation. The term “computer-readable medium” may include, but is notlimited to, portable or fixed storage devices, optical storage devices,and various other mediums capable of storing, containing or carryinginstruction(s) and/or data.

Furthermore, at least some portions of example embodiments may beimplemented by hardware, software, firmware, middleware, microcode,hardware description languages, or any combination thereof. Whenimplemented in software, firmware, middleware or microcode, the programcode or code segments to perform the necessary tasks may be stored in amachine or computer readable medium such as a computer readable storagemedium. When implemented in software, processor(s), processingcircuit(s), or processing unit(s) may be programmed to perform thenecessary tasks, thereby being transformed into special purposeprocessor(s) or computer(s).

A code segment may represent a procedure, function, subprogram, program,routine, subroutine, module, software package, class, or any combinationof instructions, data structures or program statements. A code segmentmay be coupled to another code segment or a hardware circuit by passingand/or receiving information, data, arguments, parameters or memorycontents. Information, arguments, parameters, data, etc. may be passed,forwarded, or transmitted via any suitable means including memorysharing, message passing, token passing, network transmission, etc.

According to at least one example embodiment, a method for generating anaerosol in an aerosol-generating system comprises storing a liquidaerosol-forming substrate in a liquid storage portion, delivering via apump the liquid aerosol-forming substrate from the liquid storageportion to an atomizer, and providing a sensor in an airflow path of theaerosol-generating system. The sensor is configured to sense a puffand/or a puff intensity of the puff. The delivery flow rate of theliquid aerosol-forming substrate to the atomizer is adjusted in responseto the sensed puff intensity.

The flow rate of the pump, by which the liquid-aerosol-forming substrateis delivered to the atomizer, is adjusted based on the intensity of thepuff of the vaper vaping the aerosol-generating system. The aerosolcomposition may remain constant independent from the inhalationintensity.

Typical puff profiles taken from a plurality of vapers may share commoncharacteristics. In particular, independent from the overall intensityof a puff, the maximum intensity of a puff is reached after about 0.3seconds to about 0.6 seconds or about 0.5 seconds after initiation ofthe puff. The maximum intensity can be used as a measure of the overallintensity of the puff. Thus, the measured airflow rate or the measuredpressure drop in the airflow path after about 0.3 seconds to about 0.6seconds or about 0.5 seconds of initiation of a puff may be used as ameasure for the overall puff intensity. The delivery flow rate of thepump is adjusted according to the puff intensity. The pump may beconfigured as a micropump.

The sensor may be configured as an airflow sensor and may measure theairflow rate. The airflow rate indicates the amount of air that is drawnthrough the airflow path of the aerosol-generating system per time bythe vaper. Depending upon the detected airflow rate, the puff intensitymay be determined. The higher the detected airflow rate is, the higherthe determined puff intensity is. The airflow rate may be detected about0.3 seconds to about 0.6 seconds or about 0.5 seconds after theinitiation of the puff. The initiation of the puff may be detected bythe airflow sensor when the airflow exceeds a desired (or, alternativelypredetermined) threshold. Initiation may also be detected upon a vaporactivating a button.

The sensor may also be configured as a pressure sensor is configured tomeasure the pressure of the air inside the aerosol-generating systemwhich is drawn through the airflow path of the system by the vaperduring a puff. The sensor may be configured to measure a pressuredifference or pressure drop between the pressure of ambient air outsideof the aerosol-generating system and of the air which is drawn throughthe system by the vaper. The pressure of the air may be detected at anair inlet, such as a semi-open inlet, a mouth end of the system, anaerosol formation chamber or any other passage or chamber within theaerosol-generating system, through which the air flows. When the vaperdraws on the aerosol-generating system, a negative pressure or vacuum iscreated inside the system, wherein the negative pressure may be detectedby the pressure sensor. The term “negative pressure” is to be understoodas a relative pressure with respect to the pressure of ambient air. Inother words, when the vaper draws on the system, the air which is drawnthrough the system has a pressure which is lower than the pressure offambient air outside of the system. The air pressure is detected about0.3 seconds to about 0.6 seconds or about 0.5 seconds after theinitiation of the puff. The initiation of the puff may be detected bythe pressure sensor if the pressure difference exceeds a desired (or,alternatively predetermined) threshold. Initiation may also be detectedupon a vaper activating a button. The higher the detected pressuredifference, i.e. the lower the pressure of the air which is drawnthrough the system, the higher the determined puff intensity.

The airflow rate or the pressure drop may also be continuously measuredby the sensor and the puff intensity may be determined on basis of thehighest airflow rate or highest pressure drop value in the course of apuff duration.

Depending upon the determined puff intensity, the delivery flow rate ofthe liquid aerosol-forming substrate from the pump towards the atomizeris adjusted by a controller. The flow rate of the liquid aerosol-formingsubstrate may be increased when a high puff intensity is determined. Theflow rate of the liquid aerosol-forming substrate may be decreased whena low puff intensity is determined. The flow rate of liquidaerosol-forming substrate is a measure of the amount of liquidaerosol-forming substrate that is pumped from the liquid storage portionby the pump to the atomizer per time. In this regard, the atomizer maybe operated for a desired (or, alternatively predetermined) time duringthe puff of a vaper. For example, the atomizer may be operated for about0.5 seconds to about 10 seconds, about 1 second to about 4 seconds, orabout 2 seconds. During this desired (or, alternatively predetermined)time, the amount of liquid aerosol-forming substrate which is pumped tothe atomizer per time may be adjusted once the puff intensity isdetermined. Alternatively, in at least one example embodiment, theatomizer may be operated for as long as a puff lasts, i.e. as long asthe vaper draws upon the aerosol-generating system. In this case, theamount of liquid aerosol-forming substrate which is pumped to theatomizer per time may be adjusted for the time during which the vaperdraws upon the aerosol-generating system once the puff intensity isdetermined.

The atomizer is configured to atomize the liquid aerosol-formingsubstrate to form an aerosol, which can subsequently be inhaled by avaper. The atomizer may comprise a heating element configured tovaporize the liquid aerosol-forming substrate, in which case theatomizer will be denoted as a vaporizer. Generally, the atomizer may beconfigured as any device which is able to atomize and/or vaporize theliquid aerosol-forming substrate. In at least one example embodiment,the atomizer may comprise a nebulizer or an atomizer nozzle based on theVenturi effect to atomize the liquid aerosol-forming substrate. Thus,the atomization of the liquid aerosol-forming substrate may be realizedby a non-thermally aerosolization technique. A mechanically vibratingvaporizer with vibrating elements, vibrating meshes, a piezo-drivennebulizer or surface acoustic wave aerosolization may be used.

In at least one example embodiment, the atomizer may be configured as avaporizer and the heating regime of the heating element may beadditionally adjusted. The heating element may be heated faster or to ahigher temperature or with a higher electric power, when a high puffintensity is determined. Consequently, if a low puff intensity isdetermined, the heating of the heating element is conducted slower, to alower temperature, or with less electric power. By adjusting the heatingregime of the vaporizer, the vaporization and/or aerosolization of theliquid aerosol-forming substrate may be adjusted to the puff intensity.Thereby, the vaper experiences a similar puff experience independent ofthe intensity, with which the vaper draws upon the system. The flow rateof the liquid aerosol-forming substrate may be adjusted together withthe adjustment of the heating regime of the vaporizer, such that thepuff experience of the user may be synergistically enhanced.

For determining the puff intensity and controlling the adjustment of thedelivery flow rate of the liquid aerosol-forming substrate, a controllermay be provided. The controller may also control the heating regime ofthe vaporizer. The controller may be operatively connected to the puffsensor. The controller may be operatively connected to the heatingelement. The controller may be configured to determine the puffintensity based on the puff sensor reading, that is, based on thedetected parameter of the sensor. The controller may be configured toadjust the delivery flow rate of the pump and the electrical powersupplied to the heating element in response to the determined puffintensity. In at least one example embodiment, when the sensor detects ahigh airflow or a large pressure difference, the controller determines ahigh puff intensity and increases the flow rate of the liquidaerosol-forming substrate. Additionally, the controller may increase theheating temperature of the heating element of the vaporizer.

For determining the puff intensity, predetermined airflow values and/orpressure values may be stored in a look-up table. The controller may beconfigured to compare the parameter values which are detected by thesensor with the values which are stored in the look-up table todetermine the puff intensity. The controller may compare the value,which is detected by the sensor after about 0.3 seconds to about 0.6seconds or about 0.5 second after the puff initiation with the valuesstored in the look-up table. The controller may also compare the highestairflow or pressure value, which is detected by the sensor after about 1second, about 0.7 seconds, or about 0.5 seconds after the initiation ofthe puff with the values stored in the look-up table. In at least oneexample embodiment, the controller may compare the highest value, whichis measured by the sensor during a puff duration with the values storedin the look-up table.

The controller may comprise a microprocessor, which may be aprogrammable microprocessor. The controller may be part of electriccircuitry, comprising further electronic components. The controller maybe configured to regulate a supply of power to the atomizer. Power maybe supplied to the atomizer continuously following activation of thesystem or may be supplied intermittently, such as on a puff-by-puffbasis. The power may be supplied to the atomizer in the form of pulsesof electrical current. The pump may be activated until the end of a puffis detected by the sensor.

The pump may be activated for the whole duration of the puff. Theheating element of the vaporizer may stay activated for an additionaldesired (or, alternatively predetermined) period of time, such as about0.5 seconds after the pump is deactivated. Upon initialization of apuff, the heating element may be pre-heated to enhance the aerosolquality of the generated aerosol.

The electrical power supplied to the heating element may be adjusted bymeans of pulse width modulation. Hereto, a switch may be provided andused for switching between supply and load on and off at a fast rate.During use of pulse width modulation, power loss in the switch is verylow. When the switch is off there is little or no current, and when itis on and power is being transferred to the vaporizer, there is almostno voltage drop across the switch. Power loss is thus in both cases verylow, increasing the efficiency of the vaporizer.

According to at least one example embodiment, an aerosol-generatingsystem is provided. The system comprises a housing with an air inlet orsemi-open inlet and an air outlet, defining an airflow path therebetween. The system further comprises an atomizer configured to atomizean aerosol-forming substrate and a pump configured to deliver a liquidaerosol-forming substrate from a liquid storage portion to the atomizer.A puff sensor is provided located in the airflow path. The puff sensoris configured to sense a puff. A controller is configured to determine apuff intensity based on the sensed purr. The delivery flow rate of theliquid aerosol-forming substrate to the atomizer is adjusted in responseto the determined puff intensity.

The atomizer of the system may comprise a heating element for vaporizingthe liquid aerosol-forming substrate, in which case the atomizer will bedenoted as a vaporizer.

The controller may be operatively connected to the puff sensor and tothe heating element. The controller may be configured to determine thepuff intensity based on the puff sensor reading. The controller may beconfigured to adjust the delivery flow rate of the pump and theelectrical power supplied to the heating element in response to thedetermined puff intensity.

An adjusted amount of the liquid aerosol-forming substrate may be pumpedfrom the liquid storage portion to a deposition region of the heatingelement. By depositing the liquid aerosol-forming substrate to theheating element directly, the liquid aerosol-forming substrate canremain in its liquid state until it reaches the heating element. In atleast one example embodiment, few residues might be produced duringliquid transport so as to allow for production of cartridges withoutatomizers. Due to the improved liquid transport, tubing segments andatomizers might not need to be disposed once the liquid storage portionis empty. By using a pump instead of a capillary wick or any otherpassive medium to draw liquid, only the actually required amount ofliquid aerosol-forming substrate may be transported to the heatingelement. Liquid aerosol-forming substrate may only be pumped upondemand, for example by a request for a puff by a vaper.

In at least one example embodiment, the aerosol-generating systemfurther comprises a chamber into which the liquid aerosol-formingsubstrate is delivered. The heating element is arranged inside thechamber and is downstream of the outlet of the liquid storage portion.

As used herein, the terms ‘upstream’, ‘downstream’, ‘proximal’,‘distal’, ‘front’ and ‘rear’, are used to describe the relativepositions of elements, or portions of elements, of theaerosol-generating system in relation to the direction in which a vaperdraws on the aerosol-generating system during vaping.

The aerosol-generating system may comprise a mouth end through anaerosol exits the aerosol-generating system. The mouth end may also bereferred to as the proximal end. During vaping, a vaper draws on theproximal or mouth end of the aerosol-generating system. Theaerosol-generating system comprises a distal end opposed to the proximalor mouth end. The proximal or mouth end of the aerosol-generating systemmay also be referred to as the downstream end and the distal end of theaerosol-generating system may also be referred to as the upstream end.Elements, or portions of elements, of the aerosol-generating system maybe described as being upstream or downstream of one another based ontheir relative positions between the proximal, downstream or mouth endand the distal or upstream end of the aerosol-generating system.

In at least one example embodiment, the aerosol-generating systemfurther comprises a tubing segment through which the liquidaerosol-forming substrate is delivered from the liquid storage portionto the atomizer. The atomizer is downstream of an open end of the tubingsegment.

The tubing segment, also referred to as tube, may be a nozzle. Thetubing segment may comprise any appropriate material, for example glass,metal, for example stainless steel, or plastics material, for examplepolyetheretherketone (PEEK). In at least one example embodiment, thetube may have a diameter of about 1 millimetre to about 2 millimetres,but other sizes are possible. In at least one example embodiment, thetubing segment comprises a capillary tube. The cross-section of thecapillary tube may be generally circular, ellipsoid, triangular,rectangular or any other suitable shape to convey liquid. At least awidth dimension of the cross-sectional area of the capillary tube ischosen to be sufficiently small such that on the one hand capillaryforces are present. At the same time, the cross-sectional area of thecapillary tube is sufficiently large such that a suitable amount ofliquid aerosol-forming substrate can be conveyed to the heating element.The cross-sectional area of the capillary tube is below about 4 squaremillimetres, below about 1 square millimetre, or below about 0.5 squaremillimetres.

The atomizer may comprise a heating coil extending from the tubingsegment in longitudinal direction. In at least one example embodiment,the heating coil may be mounted transverse to the tubing segment. Theheating coil may overlap with the open end of the tubing segment for upto about 3 millimetres or up to about 1 millimetre. In at least oneexample embodiment, there may be a distance between the open end of thetubing segment and the heating coil. The length of the heating coil maybe about 2 millimetres to about 9 millimetres or about 3 millimetres toabout 6 millimetres. The diameter of the heating coil may be chosen suchthat one end of the heating coil can be mounted around the tubingsegment. The diameter of the heating coil may be about 1 millimetre toabout 5 millimetres, or about 2 millimetres to about 4 millimetres.

In at least one example embodiment, the aerosol-generating systemcomprises a main unit and a cartridge. The cartridge is removablycoupled to the main unit. The main unit comprises a power supply. Theliquid storage portion is provided in the cartridge. The pump is in themain unit. In at least one example embodiment, the main unit furthercomprises the atomizer. The main unit may comprise a tubing segment.

The aerosol-generating system may comprise a power supply, such as abattery, within the main body of the housing. In at least one exampleembodiment, the power supply may be another form of charge storagedevice such as a capacitor. The power supply may require recharging andmay have a capacity that allows for the storage of enough energy for oneor more vaping experiences. In at least one example embodiment, thepower supply may have sufficient capacity to allow for the continuousgeneration of aerosol for a period of about six minutes or for a periodthat is a multiple of about six minutes. In at least one exampleembodiment, the power supply may have sufficient capacity to allow foran estimated desired (or, alternatively predetermined) number of puffsor discrete activations of the heater assembly.

For allowing ambient air to enter the aerosol-generating system, a wallof the housing of the aerosol-generating system, such as a wall oppositethe atomizer or a bottom wall, is provided with at least one semi-openinlet or air inlet. The semi-open inlet allows air to enter theaerosol-generating system. The wall may not allow air or liquid to leavethe aerosol-generating system through the semi-open inlet. A semi-openinlet may be a semi-permeable membrane that is permeable in onedirection only for air, but is air- and liquid-tight in the oppositedirection. A semi-open inlet may be a one-way valve. In at least oneexample embodiment, the semi-open inlets allow air to pass through theinlet only if specific conditions are met, for example a minimumdepression in the aerosol-generating system or a volume of air passingthrough the valve or membrane.

The liquid aerosol-forming substrate is a substrate configured torelease volatile compounds that can form an aerosol. The volatilecompounds may be released by heating the liquid aerosol-formingsubstrate. The liquid aerosol-forming substrate may comprise plant-basedmaterial. The liquid aerosol-forming substrate may comprise tobacco. Theliquid aerosol-forming substrate may comprise a tobacco-containingmaterial containing volatile tobacco flavour compounds, which arereleased from the liquid aerosol-forming substrate upon heating. Theliquid aerosol-forming substrate may alternatively comprise anon-tobacco-containing material. The liquid aerosol-forming substratemay comprise homogenized plant-based material. The liquidaerosol-forming substrate may comprise homogenized tobacco material. Theliquid aerosol-forming substrate may comprise at least oneaerosol-former. The liquid aerosol-forming substrate may comprise otheradditives and ingredients, such as flavourants.

The aerosol-generating system may be an electrically operatedaerosol-generating system. In at least one example embodiment, theaerosol-generating system is portable. The aerosol-generating system mayhave a size comparable to a cigar or cigarette. The aerosol-generatingsystem may have a total length ranging from about 30 millimetres toabout 150 millimetres. The aerosol-generating system may have anexternal diameter ranging from about 5 millimetres to about 30millimetres.

The cartridge may be a disposable article to be replaced with a newcartridge once the liquid storage portion of the cartridge is empty orbelow a minimum volume threshold. In at least one example embodiment,the cartridge is pre-loaded with liquid aerosol-forming substrate. Thecartridge may be refillable.

The aerosol-generating system may be in a preheat mode when theaerosol-generating system has been powered on. The electric circuitryheats the heating element constantly until the heating element reaches adesired (or, alternatively predetermined) operating temperature. Theoperating temperature may be about 250° C. The duration of the preheatmode may be controlled by the preheat duration parameter. In at leastone example embodiment, the preheat duration parameter is set to a valueranging from about 3 seconds to about 4 seconds. Under normalconditions, the aerosol-generating system may reach its operatingtemperature within the preheat duration. Once the operating temperatureis reached, the pump may be activated for at least one pump cycle totransport an adjusted amount of liquid aerosol-forming substrate throughthe pump to make the aerosol-generating system ready to use.

The aerosol-generating system may then enter the temperature hold modeuntil the electric circuitry detects a puff or until a hold timeoutduration is reached as defined by the value of the hold timeout durationparameter.

In temperature hold mode, a sequence of heating pulses may be sent tothe heating element which can have the effect of maintaining a lowerpreheat temperature below the operating temperature until the holdtimeout is reached. The lower preheat temperature may be about 150° C.

Once a puff has been detected and the heating element has reached theoperating temperature, the controller may activate the pump and set anadjusted flow rate for delivering liquid aerosol-forming substrate tothe deposition region of the heating element for the duration of thepuff. The flow rate depends upon the puff intensity.

Once the puff stops, the aerosol-generating system may return to thetemperature hold mode. If no input is detected during the temperaturehold duration, the device may automatically cool down and wait forinput.

FIG. 1 is an illustration of an aerosol-generating system. Theaerosol-generating system comprises a main body with a housing 2. Withinthe housing 2, a liquid storage portion 4 is provided. The liquidstorage portion 4 holds a liquid aerosol-forming substrate 6. The liquidstorage portion 4 is not part of the main body and may be provided as acartridge which can be disposed when the liquid aerosol-formingsubstrate 6 in the liquid storage portion 4 is depleted. After disposalof the liquid storage portion 4, a new liquid storage portion 4 isinserted into the housing 2.

The main body of the aerosol-generating system comprises a battery 8,which is connected to a controller 10. The controller 10 is configuredto control the flow of electric current from the battery 8 viaconductors 12 to a heating element 14 of a vaporizer. The controller 10is further connected to a pump 16, which is provided to pump liquidaerosol-forming substrate 6 from the liquid storage portion 4 to theheating element 14 of the vaporizer. The pump 16 is configured as amicropump inside the main body of the aerosol-generating system.

The aerosol-generating system further comprises a pressure or airflowsensor 22, which is arranged in an airflow path near an air inlet 18.The sensor 22 is configured to detect the airflow and/or pressure of theair within the airflow path, which is drawn by a vaper towards a mouthend 20 of the aerosol-generating system. In this regard, the sensor 22detects an airflow rate or pressure drop in the airflow path and thecontroller 10 determines the puff intensity based upon the sensor 22reading after 0.5 seconds after the puff initiation. In at least oneexample embodiment, the controller 10 compares the output from thesensor 22 with values of airflow rates and/or pressures contained in alook-up table 24 that may be stored in a memory 26. The airflow ratedenotes the amount of air per unit of time that flows through theairflow path.

The controller 10 is configured to adjust the delivery flow rate ofliquid aerosol-forming substrate 6 from the liquid storage portion 4 tothe heating element 14 of the vaporizer. The controller 10 increases thedelivery flow rate if a high puff intensity is determined and decreasesthe delivery flow rate if a low puff intensity is determined. A highpuff intensity is determined by the controller 10 when a high airflowrate or a high pressure drop is determined based on the output from thesensor 22.

In at least one example embodiment, the controller 10 is furtherconfigured to control the heating temperature of the heating element 14of the vaporizer. The controller 10 increases the heating temperature ifa high puff intensity is determined and decreases the heatingtemperature if a low puff intensity is determined.

After a puff initiation is detected by the sensor or a button, which thevaper presses, the controller controls the pump 16 to pump the liquidaerosol-forming substrate 6 from the liquid storage portion 4 to theheating element 14 of the vaporizer. The controller 10 adjusts thedelivery flow rate based upon the determined puff intensity. The liquidaerosol-forming substrate 6 is vaporized by the vaporizer to form anaerosol. The aerosol is formed by mixing of the vaporized liquidaerosol-forming substrate 6 with ambient air which is drawn through theair inlet 18. The generated aerosol is subsequently inhaled by a vaperthrough the mouth end 20.

FIG. 2 shows a diagram of measurements of pressure drop values, measuredin hectopascal (1 hPa=100 Pa), over the time, measured in milliseconds,of a puff. The different measurements show that around about 0.3 secondsto about 0.6 seconds, and around about 0.5 seconds after the initiationof the puff, the pressure difference is the highest. After that, thepressure difference slowly decreases. Thus, the controller determinesthe puff intensity by evaluating the sensor measurement after about 0.5seconds after the puff initiation.

The exemplary embodiments described above illustrate but are notlimiting. In view of the above discussed exemplary embodiments, otherembodiments consistent with the above exemplary embodiments will now beapparent to one of ordinary skill in the art.

We claim:
 1. An aerosol-generating system, the system comprising: a pumpconfigured to deliver an aerosol-forming substrate to a vaporizer; apuff sensor in an airflow path, the puff sensor configured to sense apuff; and a controller configured to determine a puff intensity based onan output from the puff sensor and adjust a delivery flow rate of thepump in response to the determined puff intensity.
 2. Theaerosol-generating system of claim 1, wherein the puff sensor is apressure sensor.
 3. The aerosol-generating system of claim 1, furthercomprising: a housing including, an air inlet, and an air outlet.
 4. Theaerosol-generating system of claim 3, wherein the vaporizer isconfigured to vaporize the aerosol-forming substrate.
 5. Theaerosol-generating system of claim 1, further comprising: a storageportion configured to contain the aerosol-forming substrate, the pumpconfigured to pump the aerosol-forming substrate from the storageportion.
 6. The aerosol-generating system of claim 1, wherein thevaporizer comprises: a heating element.
 7. The aerosol-generating systemof claim 6, wherein the heating element is a heating coil.
 8. Theaerosol-generating system of claim 7, further comprising: a channelthrough which the aerosol-forming substrate is delivered to thevaporizer.
 9. The aerosol-generating system of claim 8, wherein thechannel has a diameter of about 1 mm to about 2 mm.
 10. Theaerosol-generating system of claim 7, wherein the heating coil extendsfrom the channel in a longitudinal direction.
 11. The aerosol-generatingsystem of claim 7, wherein the heating coil extends transverse to thechannel.
 12. The aerosol-generating system of claim 7, wherein theheating coil overlaps with an open end of the channel for up to about 3mm.
 13. The aerosol-generating system of claim 7, wherein the heatingcoil is mounted around the channel.
 14. The aerosol-generating system ofclaim 1, wherein the pump is a micropump.
 15. The aerosol-generatingsystem of claim 6, wherein the controller is further configured toadjust electrical power supplied to the heating element in response tothe determined puff intensity.